Hello

Determine the coordinates of the point on the graph f(x) = (2x+1)^0.5 where the tangent line is perpendicular to the line 3x +y +4 = 0

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This is what I did so far

f'(x) = 0.5 (2x+1) ^-0.5 (2)

= 1 / (2x+1) ^0.5

Not sure what to do after